fix oracle date parsing in Java1.6

looks like later versions of Java ignore a "+" at the beginning of a
number

h2/src/main/org/h2/util/ToDateTokenizer.java

@@ -6,7 +6,6 @@
 package org.h2.util;
 
 import static java.lang.String.format;
-
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
@@ -21,7 +20,6 @@ import java.util.Map;
 import java.util.TimeZone;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
-
 import org.h2.api.ErrorCode;
 import org.h2.message.DbException;
 
@@ -143,6 +141,10 @@ class ToDateTokenizer {
                 case IYYY:
                     inputFragmentStr = matchStringOrThrow(
                             PATTERN_FOUR_DIGITS, params, formatTokenEnum);
+                    // only necessary for Java1.6
+                    if (inputFragmentStr.startsWith("+")) {
+                        inputFragmentStr = inputFragmentStr.substring(1);
+                    }
                     dateNr = Integer.parseInt(inputFragmentStr);
                     // Gregorian calendar does not have a year 0.
                     // 0 = 0001 BC, -1 = 0002 BC, ... so we adjust